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New science from Juno probe – ‘like a whole new Jupiter’

There’s the usual speculative talk of exotic materials, mysterious dynamos and so forth, but the probe is delivering plenty of data for scientists to analyse and ponder over.

When NASA’s Juno spacecraft recently flew over the poles of Jupiter, researchers were astonished, as if they had never seen a giant planet before, says Phys.org.

And in a sense they hadn’t.

The pictures were unlike anything in the history of planetary exploration.

Juno entered orbit on the 4th of July 2016 and later found Jupiter’s poles covered in nearly continent-sized storms that are densely clustered and rubbing together in a mind-blowing swirl.

“It’s like a whole new Jupiter,” says Scott Bolton, Juno’s principal investigator from the Southwest Research Institute. “The clouds were amazing.”

What’s striking about Jupiter’s polar storms is that there are actually multiple cyclones at each pole. So instead of having one polar vortex like Earth, Jupiter was observed to have as many as eight giant swirls moving simultaneously on its north pole and as many as five on its south pole.

Even more amazing things are lurking below. Researchers have long wondered about the giant planet’s hidden interior. How far down do Jupiter’s continent-sized storms descend? And what is the exotic material near the planet’s core?

Deep inside Jupiter, high temperatures and crushing pressures transform Jupiter’s copious supplies of gaseous molecular hydrogen into an exotic form of matter known as liquid metallic hydrogen. Think of it as a mashup of atomic nuclei in a sea of electrons freely moving about. Jupiter’s powerful magnetic field almost certainly springs from dynamo action in Jupiter’s interior, the process by which the motion of this electrically-conducting fluid is converted into magnetic energy. The exact location within the interior is a mystery that researchers are still working to solve.

A planet’s magnetic field gets weaker as you get farther from its core. Jupiter’s magnetic field is 10,000 time stronger than that of Earth! However when measured at the cloudtops, Jupiter’s magnetic field is only 20 times greater than what we measure on Earth’s surface. This is due to Jupiter being so much larger than Earth.

Astronomers have long known that Jupiter has the most intense planetary magnetic field in the solar system. But according to Jack Connerney, Juno deputy principal investigator at NASA’s Goddard Space Flight Center, “Juno’s magnetometers indicate that Jupiter’s magnetic field is even stronger than we thought.”

“Moreover, the magnetic field looks lumpy,” he says. “It is stronger in some places and weaker in others. This uneven distribution suggests that the field might be generated by dynamo action closer to the surface, above the layer of metallic hydrogen.”

Jupiter’s magnetic field is home to the biggest and most powerful auroras in the solar system. Unlike Earth, which lights up in response to solar activity, Jupiter makes its own auroras. It does this by tapping into power generated by its own spinning magnetic field. Induced electric fields accelerate particles toward Jupiter’s poles where the aurora action takes place.

1995:Galileo began its tour of the jovian system in December 1995. Carefully designed orbits allowed the spacecraft to observe Jupiter’s atmosphere, revealing numerous large thunderstorms many times larger than those on Earth, with lightning strikes up to 1,000 times more powerful than terrestrial lightning.

Plenty of electricity there.
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Flux tube and plasma torus [Note: Io is Jupiter’s nearest large moon]An electric current of five million amperes flows along Io’s flux tube. It connects Io to the upper atmosphere of Jupiter, like a giant umbilical cord. The plasma torus is centered near Io’s orbit, and it is about as thick as Jupiter is wide. The torus is filled with energetic sulfur and oxygen ions that have a temperature of about 100 thousand kelvin. Because the planet’s rotational axis is tilted with respect to the magnetic axis, the orbit of the satellite Io (dashed line) is inclined to the plasma torus. Currents are generated as the plasma from the Io torus spreads into the vast, rotating magnetosphere of Jupiter, and these currents couple the moon to Jupiter’s atmosphere where they stimulate a ring, or oval, of aurora emissions.

Yes, it means something to me. The atomic hydrogen is crushed so closely together that the electrons are shared in a big cloud and all the nuclei are shoved as close as the nuclear forces will allow them. (i.e. the nuclei are in a ‘mash up’ together and the electrons are in a metal like shared cloud free to move around to near any of the nuclei).

In metals, the nuclei are packed in crystals but the outer electrons make a cloud or sea of charge that is free to move about. This is just saying the same state is reached by crushing the hydrogen under enough pressure.

A conductive ball of liquid self generates a mag field which then causes currents that create more mag field that…

It self starts as the initial state is never exactly zero even magnetic field.

It’s easy to create a magnetic field by using a battery to force an electric current through a loop of wire. But Earth’s core, a rotating mix of iron and nickel with internal flows driven by the passage of heat, has no battery and no wires. Instead, it creates magnetism by means of self-sustaining feedback. Liquid metal moving through a magnetic field generates a current, similar to that induced in the moving coil of an electric generator. That current in turn generates the magnetic field. This “self-generation” mechanism can dramatically amplify the small, random fields that always exist in magnetic materials. To do this, though, the flow must be both complex, mixing up the longitudinal and latitudinal directions, and rapid, “tangling up” magnetic field lines faster than they can untangle.

To demonstrate self-generation in the lab, two teams in 2000 forced liquid sodium into complex but non-turbulent flows using physical barriers that deflected the fluid along precisely defined paths. Now the French VKS collaboration–which includes the École Normale Supérieure (ENS) institutes in Paris and Lyon and the Atomic Energy Commission (CEA) in Saclay–has created a self-generating magnetic field with a less contrived flow. They placed disks, equipped with curved vanes, at each end of a half-meter long cylindrical tank filled with liquid sodium. Rotation of these “propellers” in opposite directions at up to 26 revolutions per second created a turbulent flow that generated a magnetic field. The field only appeared when the propellers were made of iron, which modifies the field near its surface.

From the post: “Moreover, the magnetic field looks lumpy,” he says. “It is stronger in some places and weaker in others. This uneven distribution suggests that the field might be generated by dynamo action closer to the surface, above the layer of metallic hydrogen.”
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Wikipedia: Jupiter’s internal magnetic field is generated by electrical currents in the planet’s outer core, which is composed of liquid metallic hydrogen.

The magnetic field around Jupiter emanates from a number of different sources, including fluid circulation at the planet’s core (the internal field), electrical currents in the plasma surrounding Jupiter and the currents flowing at the boundary of the planet’s magnetosphere.